Thread: The Search for the Perfect Lug Rig Boom for A goat Island Skiff

Just down bendy. From observing my original boom the side bendy appeared minimal even when down bendy was at crazy scary levels. Sooo me thinks if down bendy is good then side is automatically taken care of. Unless you have some ridiculously tall and skinny boom.

Hmmmmmmmm

If I remember correctly FrankenBoom has minimal down bendy but still retained side bendy. I will fool with it and get info up on the wiki when I get home next.

Originally Posted by SimonLew

Just down bendy. From observing my original boom the side bendy appeared minimal even when down bendy was at crazy scary levels. Sooo me thinks if down bendy is good then side is automatically taken care of. Unless you have some ridiculously tall and skinny boom.

I think this is likely to be correct!

MIK

Interesting. My booms show little or no "down bendy" when sailing. "Side bendy" is much more pronounced... enough to the point that I've referred to my original box-boom as the Banana Boom.

Why doesn't side bend matter? Doesn't it affect sail shape? Seems that it would but I don't know enough to figure out how it affects sail shape or trim.

Well .... that is data that scuttles the argument!

Have to design for both side bend and vertical bend!

The main problem of any bend is that if too much the clew and tack move closer together. For modest amounts of bend the amount is very tiny. But at some point ... as the bend gets larger it starts to have a significant effect on the depth of the sail.

For a few years people thought that it was great to get some automatic response in a boom with a tracked mainsail foot - to "flatten the foot". But it was one of those backward bits of thinking ...

Generally when there is enough wind to induce boom bend there is a chop and also a problem with heeling moment.

So to flatten out the top of the sail (or get rid of it by reefing) and have more depth in the bottom near the boom helps a great deal. At least for rigs with a mast and boom on the front sail.

To flatten the foot ... everyone just pulls the outhaul to what they want and have very stiff booms.

MIK

Generally in conditions you want the boom to

No side bendy to report from Hakuna Matata.

FrankenBoom:

Doug-Fir Laminated
2 vertical staves sandwiched between 2 horizontal staves with the lower horizontal stave coming up short of the ends by 40.5cm (16") on each end.

Main Body:
35mm wide
73mm tall

Ends: (16"/40.5cm)
35mm wide
56mm tall

Weight: 12.5 lbs/5.7kg (includes boom, 3 cheek blocks, jam cleat, and steel wire tack-attachment point)

Down bendy with 30lbs/14kg = 5mm or less (rope attachment of weight deflected measuring line upwards)

Side bendy with 30lbs/14kg = 37mm

Now that is a serious boom! Can you add two chunky electrodes where the approximate "neck" is?

My new boom is rigged but untested. Clanking around in the garage last night, tying knots and thinking "go fast" thoughts. No steel wire for the tack - four wraps of 4mm dyneema. I must say, it looks very sexy.

Christophe, did you try Wood's tight traveller rec yet?

I didn't really understand the "tight traveller" concept. Are we talking about limited travel? I have had limited travel for two years now, and it works great-- or are we talking about cranking down on the tension on the traveler?

As far as FrankenBoom is concerned, it's definitely a beefy boom. I was surprised at the negligible down bendy. The thing supports my weight.

Looking forward to pics of "The Slab"

I think our booms should get in a ring and wrastle it out!

It's a bit opposite of restricting the traveller. The traveller line is tight gunwale to gunwale, so that the traveller block can slide unrestricted to the gunwale when the sheet is under full tension. After reading his rec, I went out and tested where my rig was at. I could not tension the leech without the block sliding inboard six inches or so, which rotated the boom and sail. For my previous weak downhaul pressure rig, this had the effect of stalling the sail when pointing on the leeward side of the mast.

As to wrastling, I think The Slab would be tapping out under a FrankenBoom triangle hold!

Like this?

[ame=http://www.youtube.com/watch?v=Oo3zWxO3yYs]Top 10 Battlebot Moments - YouTube[/ame]

Or like a pinyata but only sticks?

YOu might end up looking like this

[ame=http://www.youtube.com/watch?v=0ionTgFxPgg]Morris dance in Botley Jenny Lind with sticks - YouTube[/ame]

Or this

[ame=http://www.youtube.com/watch?v=i9SSOWORzw4]monty python - fish dance - YouTube[/ame]

Frankenboom LIVES!

How come FrankenBoom isn't listed in the wiki?

And what's with the 14Kg for checking deflection? Thought we were 'standardized' at 10Kg...

Hehe ... BobWes

I think you have rights to edit the base google doc still
https://docs.google.com/document/d/1...hN3FeO5W4/edit

If anyone else established in the group wants to sort out the document in any way I can add you as an editor!

It would be truly wonderful if the information was pulled together a bit better - so an EDITOR would be really valuable!!!

Oh ... To bring back to the standard just divide by 1.4. Unless the boom is cracking up, it will follow the rules of classical mechanics close enough for our methods of measurement! So correct it and put a note under the table about the 14kg.

MIK